Nuclear regulators will discuss the risk of “pressurized thermal shock,” one of the biggest fears anti-nuclear groups have about the Palisades nuclear power plant during an online meeting Tuesday.
Over time the radiation, extreme pressure and heat from the nuclear reactor wear on the metal vessel that contains it. That’s called embrittlement.
The more embrittled the vessel, generally the higher the risk of pressurized thermal shock. That's a phenomenon that could happen during an emergency shutdown where cold water (about 40 degrees) would get dumped into the hot vessel (about 550 degrees) and cause it to crack.
The Nuclear Regulatory Commission defined it this way:
Pressurized thermal shock is a phenomenon that would occur in a rare accident scenario in which a large amount of cold water has to be injected into the reactor resulting in its rapid cooling. This rapid cooling increases the stresses on the vessel and could challenge the vessel’s integrity.
NRC staff last year said Palisades has the most embrittled reactor vessel of any in the nation. Several South Haven area residents, environmentalists, and others bring up their concerns about that at most every public meeting. The NRC says they’re hoping the online meeting Tuesday will be informative to the community.
The Palisades plant was recently upgraded from one of the worst safety performance levels of any plant in the country following a series of problems in 2011.
“It’s not related to plant performance or anything like that,” NRC spokeswoman Viktoria Mitlyng said, “It’s a regulatory concern of which we have been aware of for a very long time.”
“2017 is the time when which the plant has to take actions to address this regulatory concern but there is nothing new. There is no imminent danger. We don’t expect the plant to shut down,” Mitlyng said.
The webinar will be held from 5-6 p.m. EDT. People interested in taking part need to pre-register by the end of Monday. More details on how to do that are available here.